<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>hasRegExpU</title>
</head>

<body>
    <script>
        function hasRegExpU() {
            try {
                var pattern = new RegExp(".", "u");
                return true;
            } catch (ex) {
                return false
            }
        }
    </script>

</body>

</html>